John Stuart Mill’s name is invoked at least once a week in newspaper articles or serious blogs. I hope it is not an exaggeration to say that anyone who claims to be even moderately well-read must have studied On Liberty at some point, or at least have an idea of Mill’s central arguments. Isaiah Berlin said in 1959 that because of his lucid prose style and deep insight into human nature Mill had achieved that rare thing and had ‘emerged as a major political thinker in our own day’; that has not changed in half a century. It is a brave biographer who tackles a subject as complex and controversial as J S Mill. Richard Reeves has succeeded in doing this with enviable style. I blush to say it so bluntly, but this is the best book I have read for a long time.